A load center provides overcurrent protection for an electrical system of a building and distributes power to various branch circuits of the electrical system. In particular, a load center may be configured either as a main breaker device including items such as a main circuit breaker, branch circuit breakers and other components or as a main lug device.
Various components of a load center such as bus bars, neutral bars and others are mounted to a base pan located in an enclosure. The base pan is fabricated from an electrically insulative material such as plastic and may be formed by an injection molding or an extrusion process. During assembly, the base pan is cut to a specific size in order to accommodate the number of circuits being utilized in a particular load center.
The bus bars serve as a common connection for two or more circuits and may be used to connect circuit breakers to service conductors and load wiring. In conventional three phase bus bar designs that include an integral stab, the bus bars are mounted in close proximity to each other and in a semi-stacked arrangement resulting in closely spaced stabs that are vertically aligned. This requires electrically isolating each bus bar from the other so as to prevent short circuiting between phase to phase or phase to ground.
However, several components and assemblies are needed to isolate the bus bars. In particular, first and second phase bus bars are attached on a front side of the base pan assembly and a third phase bus bar is mounted on a back side by inserting stabs through slots that align with the front mounted bus bars. The third phase bus bar is isolated by attaching an insulator sheet that is specifically sized for the bus bar being used. Use of the insulator sheet requires several fasteners in order to assemble the insulator sheet to the back side of the base pan. Fasteners are also required to attach the first and second phase bus bars to the front side of the base pan. Further, additional components and fasteners are needed to isolate a third phase load strap and to define a wire-way on the base pan in order to meet safety standards. Such additional components and fasteners increase complexity in assembling three phase load centers. In addition, having to provide specifically sized components for various length load center interiors creates inventory management challenges.